I think that a small number of companies may be dissuaded from tightly linking their code to GPL code due to concerns of distribution constrained by the GPL.

But it's clear that a number of companies *like* the reciprocal nature of the GPL, as demonstrated by their releasing large bodies of their own code under the license. See, e.g., SugarCRM, CUPS, and MySQL.

The GPL allows them to release code they have created for their own products, without worrying that a competitor can instantly leapfrog their product by making a proprietary fork of it, as would be possible under the BSD, Apache or similar licenses.

Some companies, like Sun, may choose licenses with even more control, like CDDL/MPL, and some may donate orphaned code like IBM with Derby. However, I think that for many, the GPL strikes a nice balance between retaining some control/rights, and giving users and developers as many rights as possible.